All Questions
Tagged with birthday combinations
12
questions
1
vote
2
answers
114
views
Miscalculating Probability of At Least $2$ People Having The Same Birthday
Regarding the problem: choosing 23 people randomly, show that there is greater than a $50$ percent chance that at least two of them will have the same birthday. What is the error in the way I'm trying ...
- 1,467
1
vote
1
answer
236
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Birthday Problem: Finding a Probability Function of an Event
Problem: Ignoring leap days, the days of the year can be numbered $1$ to $365$. Assume that birthdays
are equally likely to fall on any day of the year. Consider a group of $n$ people, of which
you ...
- 67
2
votes
1
answer
62
views
My try of the Birthday Paradox
I have seen the solution of the paradox on Wikipedia, but before that I tried it out myself. But I got my answer wrong with my approach.
To calculate the probability of no two people in a group of 23 ...
- 21
3
votes
1
answer
572
views
Birthday problem: solving with permutations vs combinations
I have a problem with an exercise:
If k people are at a party, what is the probability that at least two of them have the same birthday? Suppose that there are n=365 days in a year and all days are ...
- 111
2
votes
2
answers
1k
views
How to calculate birthday problem for collisions of a random number generator
I'm creating a script that generates random numbers for invoices as fully described here.
The current version of my script includes logic to prevent collisions, but this means that every time there is ...
3
votes
1
answer
232
views
Birthday paradox question
I am solving the question:
How large must a class be to make the probability of finding two people with the same birthday at least 50%?
The first solution I came up with is rather simple. It's based ...
- 677
0
votes
2
answers
696
views
What is the probability that in a company of $500$ people, only two persons will have birthdays on New Year’s Day?
What is the probability that in a company of 500 people, only two persons will have birthdays on New Year’s Day?
I feel the answer is
=$\frac{1}{365}\cdot\frac{1}{365}\cdot\frac{364}{365}\cdot\frac{...
- 379
5
votes
2
answers
117
views
Probability no male- female pairs share same birthday
There are 8 people in a room. There are 4 males(M) and 4 females(F). What is the probability that there are no M-F pairs that have the same birthday ? It is OK for males to share a birthday and for ...
- 139
1
vote
0
answers
104
views
Generalized birthday paradox, expected number of birthday days
Suppose we have m objects and we draw one uniformly n times with replacement. Some objects will be drawn at least once, some never. What is the expected value of the number of objects that are drawn, ...
- 235
1
vote
1
answer
1k
views
Probability - The birthday problem
You go to a party which has 1000 guests (including you).
a) What is the probability that exactly one other guest has the same birthday as you?
b) What is the probability that at least two other ...
- 509
8
votes
1
answer
615
views
The birthday problem when the order is not important
Suppose that we are interested in the probability that in a set of $n$ randomly chosen people at least two people share the same birthday. We make the assumption that each day of the year (except ...
- 17.4k
8
votes
2
answers
750
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Birthday "Paradox" - another, different, version!
Background
Many people are familiar with the so-called Birthday "Paradox" that, in a room of $23$ people, there is a better than $50/50$ chance that two of them will share the same birthday. ...
- 181